Semiconductor snail lasers

Abstract

A modified ring laser geometry is presented to promote stable unidirectional lasing. The effects of directional coupling and facet reflectivities are investigated with respect to quantum efficiency, directionality, and side-mode suppression ratio of the lasing spectra. Simulation and experimental results are presented showing single mode ͑Ͼ20 dB side-mode suppression ratio͒, unidirectional lasing on an InP based multiple quantum well material.

Rate-equation theory of a feedback insensitive unidirectional semiconductor ring laser

“…This kind of sensitivity can be reduced considerably by applying a one-sided strong reflector [5], but EOF exceeding 30 dB can still lead to unstable behavior. In this respect, we mention [6], who developed a "snail" laser consisting of a ring laser with the CW output blocked by a reflector. This laser operates unidirectionally, but the EOF sensitivity is not discussed.…”

Unidirectional, widely-tunable and narrow-linewidth heterogeneously integrated III-V-on-silicon laser

“…A narrower linewidth can be achieved because of the absence of spatial hole burning [18][19], together with a more smooth output power versus wavelength characteristic, as there is no competition between the CW and the CCW mode. For these reasons several methods have been evaluated to reach unidirectional lasing, including the use of an S-bend waveguide structure inside the ring laser cavity [17], a snail shape laser [20] or an external reflector coupling the CW and the CCW mode [21]. The latter approach is followed in this paper.…”